Low-field AC susceptibility study of critical current density in Eu: 123 and Bi: 2223 superconductors

Low-field ACsusceptibility measurements have been made, at different values of ACfield amplitude Hm (26–600 A/m), on Eu:123 and Bi:2223 samples. Analysis of the temperature dependence of the ACsusceptibility has been done employing Beans’ critical state model. The intergranular critical current density (Jc) is calculated as a function of both Hm and temperature for both samples, respectively. It is found that Jc increases with increasing Hm for both samples and its values are generally higher in Bi sample than in Eu sample. Our results are discussed in terms of zero-temperature pinning potential bI(0) in both systems. r 2001 Elsevier Science B.V. All rights reserved.